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611.
Robert K. Thomson 《Journal of organometallic chemistry》2011,696(25):3966-3973
Reaction of (C5Me5)2Lu(Me)(μ-Me)Li(THF)3 (2) with excess 12-crown-4 affords the new separated ion pair complex, [Li(12-crown-4)2][(C5Me5)2LuMe2] (3), in excellent yield. This complex reacts with 2,6-diisopropylaniline and phenylacetylene to give the methyl amide complex [Li(12-crown-4)2][(C5Me5)2Lu(Me)(NH-2,6-iPr2C6H3)] (4) and the bis(acetylide) complex [Li(12-crown-4)2][(C5Me5)2Lu(C≡C-Ph)2] (5), respectively. Attempts to promote methane loss from complexes 3 and 4 to generate a lutetium methylidene or imido complex, respectively, were unsuccessful. The ability of the bis(acetylide) complex 5 to act as a π-tweezer complex was also explored. Reaction between [Li(12-crown-4)2][(C5Me5)2Lu(C≡C-Ph)2] (5) and CuSPh gave only intractable lutetium products and the copper(I) species [Li(12-crown-4)2][Cu(C≡C-Ph)2] (8). The new lutetium complexes have been characterized by elemental analysis and NMR spectroscopy. Finally, the X-ray crystal structures of (C5Me5)2Lu(Me)(μ-Me)Li(THF)3 (2), [Li(12-crown-4)2][(C5Me5)2LuMe2] (3), [Li(12-crown-4)2][(C5Me5)2Lu(Me)(NH-2,6-iPr2C6H3)] (4), [Li(12-crown-4)2][(C5Me5)2Lu(C≡C-Ph)2] (5), and [Li(12-crown-4)2][Cu(C≡C-Ph)2] (8) are also reported. 相似文献
612.
B. M. Crosland M. R. Johnson K. A. Thomson 《Applied physics. B, Lasers and optics》2011,102(1):173-183
Laser-induced incandescence (LII) is an optical measurement technique capable of measuring soot volume fraction over a wide
range of conditions. However, development of two-dimensional auto-compensating LII (2D-AC-LII) in the literature has been
limited and until now, instantaneous measurements have not been demonstrated. In this paper, we successfully demonstrate instantaneous
2D-AC-LII soot volume fraction (SVF) measurements in an ethylene-air co-annular diffusion flame. Results were then used to
support a detailed uncertainty analysis based on a Monte-Carlo simulation. Agreement between both the instantaneous and average
SVF measurements with published data from attenuation measurements under identical conditions was found to be good. Uncertainties
are discussed both in terms of an overall accuracy of the SVF measurement, which is strongly dominated by uncertainty in the
optical properties of soot, and the comparative uncertainties with optical properties fixed. The uncertainty in an instantaneous
2D determination of SVF for a comparative measurement is dominated by photon shot noise, and in regions of high soot volume
fraction it is below 25% (95% confidence interval). Shot noise uncertainty could be further reduced with additional pixel
averaging at the expense of spatial resolution. This diagnostic shows significant promise for quantitative planar soot concentration
measurements within turbulent flames. 相似文献
613.
The primary literature concerning the combinatorial synthesis of organophosphorus compounds is reviewed and discussed. The subject matter is divided into three main sections describing the solid phase, solution phase and solvent-free synthesis of phosphorus containing organic molecules. The review covers the synthesis of compounds in which the final products contain phosphorus-carbon bonds, primarily phosphonates, phosphinates, phosphine oxides and phosphines. 相似文献
614.
Abraham E Brock EA Candela-Lena JI Davies SG Georgiou M Nicholson RL Perkins JH Roberts PM Russell AJ Sánchez-Fernández EM Scott PM Smith AD Thomson JE 《Organic & biomolecular chemistry》2008,6(9):1665-1673
The highly diastereoselective anti-aminohydroxylation of (E)-gamma-tri-iso-propylsilyloxy-alpha,beta-unsaturated esters, via conjugate addition of lithium (S)-N-benzyl-N-(alpha-methylbenzyl)amide and subsequent in situ enolate oxidation with (+)-(camphorsulfonyl)oxaziridine, has been used as the key step in the asymmetric synthesis of N,O,O,O-tetra-acetyl d-lyxo-phytosphingosine (20% yield over 7 steps), the anhydrophytosphingosine jaspine B (10% yield over 9 steps), 2-epi-jaspine B (14% yield over 9 steps), and the Prosopis alkaloid deoxoprosophylline (26% yield over 7 steps). 相似文献
615.
Aciro C Claridge TD Davies SG Roberts PM Russell AJ Thomson JE 《Organic & biomolecular chemistry》2008,6(20):3751-3761
Treatment of 3-aminocyclohex-1-enes with mCPBA in the presence of trichloroacetic acid gives the corresponding 1,2-anti-2,3-syn-1-trichloroacetoxy-2-hydroxy-3-aminocyclohexane with high levels of diastereoselectivity (90% de). This is consistent with a mechanism of oxidation involving hydrogen-bonded delivery of the oxidant by the allylic ammonium ion formed in situ, followed by highly regioselective ring-opening of the intermediate epoxide by trichloroacetic acid. The effect of conformational constraints upon the oxidation reaction is also examined. 相似文献
616.
A one-pot synthesis of allenes by the 2-nitrobenzenesulfonylhydrazide-mediated coupling of hydroxyaldehydes or ketones with alkynyl trifluoroborate salts is reported. This mild process involves in situ formation of a sulfonylhydrazone that reacts with alkynyl trifluoroborates to generate a transient propargylic hydrazide species. Decomposition of this unstable hydrazide via an intermediate monoalkyldiazine produces the allene products through an alkene walk mechanism. 相似文献
617.
618.
Davies SG Foster EM Frost AB Lee JA Roberts PM Thomson JE 《Organic & biomolecular chemistry》2012,10(30):6186-6200
"Matching" and "mismatching" effects in the doubly diastereoselective conjugate additions of the antipodes of lithium N-benzyl-(N-α-methylbenzyl)amide to enantiopure cis- and trans-dioxolane containing α,β-unsaturated esters have been investigated. High levels of substrate control were established first upon conjugate addition of achiral lithium N-benzyl-N-isopropylamide to both tert-butyl (S,S,E)-4,5-O-isopropylidene-4,5-dihydroxyhex-2-enoate and tert-butyl (4R,5S,E)-4,5-O-isopropylidene-4,5-dihydroxyhex-2-enoate. However, upon conjugate addition of lithium (R)-N-benzyl-(N-α-methylbenzyl)amide and lithium (S)-N-benzyl-(N-α-methylbenzyl)amide to these substrates, neither reaction pairing reinforced the apparent sense of substrate control. These reactions do not, therefore, conform to the classical doubly diastereoselective "matching" or "mismatching" pattern usually exhibited by this class of reaction. A comparison of these reactions with the previously reported doubly diastereoselective conjugate addition reactions of lithium amide reagents to analogous substrates is also discussed. 相似文献
619.
Some 1,2-diarylimidoyl radicals were generated in the gas-phase by intramolecular radical translocation from ortho-imino-aryloxyl radicals, in turn generated under flash vacuum pyrolysis (FVP) conditions. The imidoyls reacted with XR ortho'-substituents in the N-aryl group to give (in most cases) modest yields of cyclisation products. Depending on the nature of the bridging atom (X), the formation of these products was initiated either by a further hydrogen atom translocation (X = CH(2)), or by ipso-attack onto the aryl group (R = Ph), or by direct substitution at the heteroatom (X = S). With XR = N(Me)Ph, the major reaction product was probably the result of a competing pathway not involving the corresponding imidoyl. 相似文献
620.
SG Davies JA Lee PM Roberts JP Stonehouse JE Thomson 《The Journal of organic chemistry》2012,77(16):7028-7045
The highly diastereoselective conjugate additions of the novel lithium amide reagents lithium (R)-N-(3-chloropropyl)-N-(α-methylbenzyl)amide and lithium (R)-N-(3-chloropropyl)-N-(α-methyl-p-methoxybenzyl)amide to α,β-unsaturated esters were used as the key steps in syntheses of the homalium alkaloids (-)-(S,S)-homaline and (-)-(R,R)-hopromine. The asymmetric synthesis of (-)-(S,S)-homaline was achieved in 8 steps and 18% overall yield, and the asymmetric synthesis of (-)-(R,R)-hopromine was achieved in 9 steps and 23% overall yield, from commercially available starting materials in each case. These syntheses therefore represent by far the most efficient total asymmetric syntheses of these alkaloids reported to date. A sample of the (4'R,4'S)-epimer of hopromine was also produced using this approach, which provided the first unambiguous confirmation of its absolute configuration and therefore that of natural (-)-(R,R)-hopromine. 相似文献